An O'Neiller is when someone is on the down and out in some shape or form, and decides to grow a beard and lets their Appearence Dishevel. It often occurs in men between the ages of 27-40, It is not to be Mistaken with mid life crisis. O'Neillers are bred from hatred and often the lack of Sexual Intercourse.

Folklore tells us that the Famous O'Neill was Roland Turlogh O'Neill, a feared Celtic warrior from Carlow town who was also said to have been a fantastic painter/decorator and a very Agressive Bearded lover.
After Patsy left him, Joe went on a terrible O'Neiller.

"God whatever you do, dont poke fun at seans beard, I hear he is in the middle of a terrible O'Neiller and is liable to do anything!
by SKetchgarda December 17, 2009
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To have a neck and neck insanely close game of Fifa/Pro evo but wait until the very last min to score the winning goal and win the game.
'Ahhh you fucker! You O'Neilled me!!'

'Shit what an epic game this has been might have to go to pen- fuck off as if you just O'Neilled me out of nowhere!!! Bastard.'

'Don't you dare O'Neill me you prick!!'
by Fifad00d August 15, 2019
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Breasts

Tatum O'Neil > Tatums > Tits

Holy fuck, her O'neils are stunning!
by Joshua James October 9, 2006
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To do none of the work, but take all the credit.
Did you see Tom as the Board of Directors meeting? He completely pulled an O'Neill on his staff!
by Truthful Observer2 December 10, 2012
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"that gut was a massive douche, what an o'neil
by goggleyes May 31, 2010
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The act of a male camply adoring his male boss.
"Jesus man, do you have to be a total O'Neil with Rob in the office?"
by LilBritain August 7, 2008
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Officer O'Neill is someone who pretends to be a cop for most of the night in 'The Groove', AKA da'club, answering all sorts of officer questions and at the end of the night tells you he just works at Verizon.
"Girl don't talk to that guy he's totally an Officer O'Neill.
by KJOYR April 10, 2015
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